US20120071819A1 - Medicament delivery devices - Google Patents

Abstract

A medicament delivery device comprises a housing, a holder within the housing for receiving a medicament cartridge, a piston rod for driving a bung of the medicament cartridge, a drive mechanism including a motor for providing an output drive to the piston rod for delivering the medicament and control means for controlling operation of the device. The device is additionally provided with a bung sensor for sensing when the piston rod is in contact with the bung and the control means is operative for advancing the drive of the piston rod towards the bung.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• The present application is a U.S. National Phase Application pursuant to 35 U.S.C. §371 of International Application No. PCT/EP2010/051272 filed Feb. 3, 2010, which claims priority to EP Patent Application No. 09001576.9 filed on Feb. 5, 2009. The entire disclosure contents of these applications are herewith incorporated by reference into the present application.
FIELD OF INVENTION
• This invention relates to medicament delivery devices for delivering medicine to the human or animal body and in particular to electronically controlled auto-injectors having a replaceable medicament cartridge. Such devices are commonly used by those with diabetes for the administration of insulin.
BACKGROUND
• Medicament delivery devices are routinely used by persons without formal medical training, i.e. patients where self-management of their condition is increasingly common. These circumstances set a number of requirements for medicament delivery devices of this kind The injector should be robust in construction, yet easy to use in terms of its operation by a user and the manipulation of the parts. In the case of those with diabetes, many users will be of impaired vision and may also be physically infirm. Devices that are too large or cumbersome may therefore prove difficult to use, particularly someone with reduced dexterity.
• U.S. Pat. No. 5,989,221 describes an electronically controlled injection device in which the readying of the device for administering and the subsequent drug delivery therefrom is controlled by an electronic control unit. Specifically, the control unit comprises a position or attitude sensor for transmitting a signal so that the readying of the device cannot take place unless the longitudinal axis of the injection cartridge is in a predetermined direction. This is in the context of removing air or mixing drug components. The control unit is also operative for driving a piston rod a predetermined distance for delivery of a drug dose.
• In such prior art devices, the user is still required to prime the device after installation of the medicament cartridge. Moreover, such devices may under dose particularly in cases where the medicament cartridge is not properly seated within the device after insertion by the user.
SUMMARY
• It is an aim of the present invention to provide a medication delivery device where replacement of the medicament cartridge is easier to carry out by the user.
• According to the present invention, there is provided a medicament delivery device for delivering a medicament to a patient, wherein the medicament delivery device comprises: a housing; a holder within the housing for receiving a medicament cartridge; a piston rod for driving a bung of the medicament cartridge; a drive mechanism including a motor for providing an output drive to the piston rod for delivering the medicament; and control means for controlling operation of the device; characterised in that:
• • a bung sensor is provided for sensing when the piston rod is in contact with the bung;
  • wherein the control means is operative for advancing drive of the piston rod towards the bung.
• In a preferred embodiment, the control means is operative for advancing the drive of the piston rod until the bung sensor senses that the piston rod is in contact with the bung. A latch sensor may be provided for sensing the position of the holder as the holder moves from an open position to a closed position. In this case, the control means is operative for advancing the drive of the piston rod only when the latch sensor senses the holder is in the closed position.
• Furthermore, a cartridge sensor may be provided for sensing the presence of a medicament cartridge in the holder. In this embodiment, the control means is operative for advancing the drive of the piston rod when the cartridge sensor senses the presence of the medicament cartridge and the latch sensor senses that the holder is in a closed position.
• The control means is operative to stop further advancement of the piston rod: a) when the bung sensor senses that the piston rod is in contact with the bung; or b) when the cartridge has moved to a seated position within the housing after initial contact between the piston rod and the bung. In this case, the force needed to actuate the bung sensor is greater than the sliding friction between the cartridge and the holder. The holder may include a door of the medicament delivery device. The control means may be operative for advancing the piston rod drive when the cartridge sensor senses that the medicament cartridge is in a predetermined (i.e. ‘correct’ or ‘seated’) position relative to the holder to deliver a dose of medicament.
• In an alternative embodiment, the latch sensor and the bung sensor may each generate sensor signals that are combined so that the combined signal sent to the control means indicates that the cartridge is present and/or in the correct position when the piston rod contacts the cartridge bung.
• In another embodiment, the control means is operative to backwind the piston rod by a predetermined amount when the bung sensor senses that the piston rod is in contact with the bung. This is advantageous in the case where the bung sensor is in the form of a dome switch or other pressure switch (including solid state switches and pressure switches), thus leaving the dome switch in an open position. For dosing, the control means drives the piston rod by an amount that compensates for this backwind.
• Any one or all of the cartridge, latch and bung sensors may be switches that signal their respective sensing function to the control means.
• Embodiments of the present invention are advantageous in that the medicament delivery device automatically advances the piston rod towards the cartridge bung when a cartridge is present and the door/holder of the injector is closed. This simplifies the number of operations for the user, including avoiding a need for the user to dial an air-shot dose to position the piston rod against the bung. Battery life is saved by avoiding drive of the piston rod when no cartridge is present. As the cartridge is properly or fully seated within the holder, a further advantage is that the likelihood of under-dosing following insertion of a new or used cartridge is reduced.
• The term “medicament delivery device” according to instant invention shall mean a single-dose or multi-dose or pre-set dose or pre-defined, disposable or re-useable device designed to dispense a user selectable or pre-defined dose of a medicinal product, preferably multiple doses, e.g. insulin, growth hormones, low molecular weight heparins, and their analogues and/or derivatives etc. Said device may be of any shape, e.g. compact or pen-type. Dose delivery may be provided through a mechanical (optionally manual) or electrical drive mechanism or stored energy drive mechanism, such as a spring, etc. Dose selection may be provided through a manual mechanism or electronic mechanism. Additionally, said device may contain components designed to monitor physiological properties such as blood glucose levels, etc. Furthermore, the said device may comprise a needle or may be needle-free. In particular, the term “medicament delivery device” may refer to a needle-based device providing multiple doses having an electrical drive mechanism, which is designed for use by persons without formal medical training such as patients. Preferably, the drug delivery device is of the automated-type, i.e. an auto-injector.
• The term “housing” according to instant invention shall preferably mean any exterior housing (“main housing”, “body”, “shell”) or interior housing (“insert”, “inner body”) having a unidirectional axial coupling to prevent proximal movement of specific components. The housing may be designed to enable the safe, correct, and comfortable handling of the drug delivery device or any of its mechanism. Usually, it is designed to house, fix, protect, guide, and/or engage with any of the inner components of the drug delivery device (e.g., the drive mechanism, cartridge, plunger, piston rod) by limiting the exposure to contaminants, such as liquid, dust, dirt etc. In general, the housing may be unitary or a multipart component of tubular or non-tubular shape. Usually, the exterior housing serves to house a cartridge from which a number of doses of a medicinal product may by dispensed.
• The term “motor” according to the instant invention shall preferably mean any motorised means for driving the gearing system and ultimately the input drive means. In the instant invention a stepper motor is preferably utilised although any means for driving the gearing system or the drive means, including a mechanical or manual actuation means, may also be incorporated into the device.
• The “proximal end” of the device or a component of the device shall mean the end, which is furthest away from the dispensing end of the device.
• The “distal end” of the device or a component of the device shall mean the end, which is closest to the dispensing end of the device.
• Devices embodying the invention may be usefully deployed in re-useable medicament delivery devices that comprise replaceable medicament cartridges and may also be deployed within an auto-injector device.
BRIEF DESCRIPTION OF THE FIGURES
• The invention will now be further described by way of example with reference to the accompanying drawings, in which like reference numerals designate like elements:
• FIG. 1 is a front view of a medicament delivery device that may include an embodiment of the present invention;
• FIG. 2 is a front view of the medicament delivery device ofFIG. 1 with a medicament cartridge door shown in an open position for receiving a medicament cartridge;
• FIG. 3 is a perspective view of a cartridge sensor/switch;
• FIG. 4 is a sectional view taken along line A-A ofFIG. 3;
• FIG. 5 is a perspective view of a bung sensor/switch; and
• FIG. 6 is a transparent view of the medicament delivery device ofFIG. 2 to show the door or holder sensor/switch.
DETAILED DESCRIPTION
• InFIG. 1, amedicament delivery device1 comprises acase2 having adisplay3 for displaying functional information relating to the operation of the medicament delivery device, including the set dose, number of doses remaining in the medicament cartridge.User interface buttons4,5 and6 are provided to allow the user to operate the injector including priming, setting a dose, opening a medicament cartridge holder anddoor7, and activating the dispensing of the set dose. A threadedneedle attachment8 is provided to which a needle can be attached for dose delivery and subsequently removed and discarded. A cover (not shown) may be provided to fit over the lower portion of thecase2 to assist in protect the device from the ingress of particles and fluid.FIG. 2 shows themedicament delivery device1 with the cartridge holder anddoor7 in an open position for receiving a replacement medicament cartridge9.
• FIG. 3 shows the cartridge holder anddoor7 in more detail, with the cartridge9 seated therein. Theholder7 is pivotally fixed to thecase2 by anattachment11 so that theholder7 can move between an open position (seeFIG. 2) and a closed position (seeFIG. 1). Anarm13 extends into thecase2 and has astop15 to limit the outward extent of the door/holder7 in the direction of arrow B. Thestop15 may also engage a latch switch orsensor16, as shown inFIG. 6, which is provided for sensing when theholder7 moves from an open or a closed position. An actuator/lever17 is provided for sensing the presence of the cartridge9 and closure of theholder7 within thecase2.FIG. 4 is a sectional view taken along line A-A ofFIG. 3 and shows the cartridge9 and the actuator/lever17. In this embodiment, thelever17 forms part of acontact switch19 that has adisplaceable contact21. Thisdisplaceable contact21 is moved to change the state of theswitch19 when the cartridge is received in theholder7. Thelever17,contact switch19 anddisplaceable contact21 together form a cartridge sensor.
• FIG. 5 is a perspective view of a telescopicpiston rod assembly23 that comprisesslidable components25 and27 which telescope within ahousing29. Theassembly23 is provided with adome switch31 at the end thereof that contacts abung20 of the cartridge9. Thedome switch31 is connected to aflexible PCB element33 that extends within thecomponents25 and27. Theelement33 emerges from the other end thereof, through thehousing29 to terminate at acontact35. Thecontact35 is coupled to a control means (not shown) that is operative for controlling the device, including the drive of the piston rod.
• FIG. 6 is a transparent view of the medicament delivery device ofFIG. 2 and shows the approximate location of the latch switch orsensor16 and thestop15 within the device. Although shown as a contact switch, it may be appreciated that the latch switch or sensor may alternatively be a mechanical latch or any other switch or sensor known in the art.
• The operation of themedicament delivery device1 is as follows. Thelatch sensor16 is provided for sensing when theholder7 moves from an open or closed position and thebung sensor31 is operative for sensing when thepiston rod25,27 is in contact with thebung20. The control means is operative for advancing drive of thepiston rod25,27 towards the bung20 provided that thelatch sensor16 senses that theholder7 has moved to a closed position. The control means is operative for advancing the drive of thepiston rod25,27 until thebung sensor31 senses that the piston rod is in contact with thebung20.
• Acartridge sensor17,19,21 is provided for sensing the presence of a medicament cartridge9 in theholder7. In this case, the control means is operative for advancing the drive of thepiston rod25,27 when thecartridge sensor17,19,21 senses the presence of the medicament cartridge and thelatch sensor16 senses that theholder7 has moved from an open position to a closed position.
• It may also be beneficial for thecartridge sensor17,19,21 to only be operative after thelatch sensor16 detects whether theholder7 has been opened or closed. While the holder is not in a closed position, it is not necessary to monitor the cartridge sensor. This may increase battery life of the device.
• In this case, in order to load a medicament cartridge9 into thedevice1, the holder7 (without a cartridge) may be opened to the position shown inFIG. 2. The movement of theholder7 from the closed position to the open position is detected by thelatch sensor16. The signal from thelatch sensor16 prompts the control means to watch thecartridge sensor17,19,21 to determine if a medicament cartridge9 is present. In the present case, no cartridge is present, so no signal is detected. Therefore, the control means does not advance the drive of thepiston rod25,27. This also aids battery life.
• A medicament cartridge9 may then be placed into theholder7 and the holder closed. As theholder7 closes, thelatch switch16 detects the movement of the holder, prompting the control means to watch thecartridge sensor17,19,21. As a medicament cartridge9 is present within theholder7 and the holder is closed, thedisplaceable contact21 is in contact with theswitch19, indicating the presence of a medicament cartridge. As both thelatch sensor16 and thecartridge sensor17,19,21 have sensed that theholder7 is closed and the medicament cartridge9 is present, the control means is operative for advancing the drive of thepiston rod25,27.
• The control means is operative to stop further advancement of thepiston rod25,27: a) when thebung sensor31 senses that the piston rod is in contact with the bung20; or b) when the cartridge9 has moved to a seated position within the holder (seeFIG. 3) after initial contact between the piston rod and the bung. In this case, the force needed to actuate thebung sensor31 is greater than the sliding friction between the cartridge9 and theholder7. Theholder7 may include a door of themedicament delivery device1. The control means may be operative for advancing the piston rod drive when thecartridge sensor17,19,21 senses that the medicament cartridge9 is in a predetermined (i.e. ‘correct’ or ‘seated’) position relative to the holder to deliver a dose of medicament.
• In an alternative embodiment, thelatch sensor16 and thebung sensor31 may each generate sensor signals that are combined so that the combined signal sent to the control means indicates that the medicament cartridge9 orholder7 is present and/or in the correct position when thepiston rod25,27 contacts thecartridge bung20.
• As thebung sensor31 is in the form of a dome switch, the control means is operative to backwind thepiston rod25,27 by a predetermined amount when thebung sensor31 senses that the piston rod is in contact with thebung20.

Claims (10)

1. A medicament delivery device for delivering a medicament to a patient, wherein the medicament delivery device comprises: a housing; a holder within the housing for receiving a medicament cartridge; a piston rod for driving a bung of the medicament cartridge; a drive mechanism including a motor for providing an output drive to the piston rod for delivering the medicament; and control means for controlling operation of the device; characterised in that:

a bung sensor is provided for sensing when the piston rod is in contact with the bung;

wherein the control means is operative for advancing the drive of the piston rod towards the bung.

2. A medicament delivery device according toclaim 1, wherein the control means is operative for advancing the drive of the piston rod until the bung sensor senses that the piston rod is in contact with the bung.

3. A medicament delivery device according toclaim 1, comprising a latch sensor for sensing the position of the holder as the holder moves from an open position to a closed position or a closed position to an open position.

4. A medicament delivery device according toclaim 3, wherein the control means is operative for advancing the drive of the piston rod when the latch sensor senses the holder is in a predetermined position or a closed position.

5. A medicament delivery device according toclaim 1, comprising a cartridge sensor for sensing the presence of a medicament cartridge in the holder.

6. A medicament delivery device according toclaim 5, wherein the control means is operative for advancing the drive of the piston rod when the cartridge sensor senses the presence of the medicament cartridge and the latch sensor senses that the holder is in a closed position.

7. A medicament delivery device according toclaim 1, wherein the control means is operative to stop further advancement of the piston rod: a) when the bung sensor senses that the piston rod is in contact with the bung; or b) when the cartridge has moved to a seated position within the housing after initial contact between the piston rod and the bung.

8. A medicament delivery device according toclaim 3, wherein the latch sensor and the bung sensor each generate sensor signals that are combined so that the combined signal sent to the control means indicates that the cartridge is present and/or in the correct position when the piston rod contacts the cartridge bung.

9. A medicament delivery device according toclaim 1, wherein the housing includes a receptacle for a user replaceable medicament cartridge.

10. An auto-injector including a medicament delivery device according toclaim 1.

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